Methane is a greenhouse gas, which is many times more potent than CO2. Its concentration in the atmosphere has doubled over the last century and continues to increase alarmingly. Ruminants are the major contributors to the biogenic methane formation, and it has been estimated that the prevention of methane formation from ruminants would almost stabilise atmospheric methane concentrations. Furthermore, the recent re-assessment of the Kyoto protocol places increased priority in decreasing methane emissions as part of a multi-gas strategy. The most effective feed additives for reducing the formation of methane contain antibiotics and ionophores which diminish the formation of microorganisms provided H2 to the methanogenes. However, the effect of antibiotic and ionophores on the formation of methane is limited.
Besides the increase of the greenhouse gases, the methane produced during the anaerobic fermentation also represents an energy loss to the host animal. Carbohydrate makes up 70-80% of the dry matter in a typical dairy cattle ration and in spite of this, the absorption of carbohydrates from the gastro-intestinal tract is normally very limited. The reason for this is the extensive fermentation of carbohydrates in the rumen resulting in production of acetate, propionate and butyrate as the main products. These products are part of the so called volatile fatty acids, VFA. The fermentation that produces the VFA, e.g. propionic acid, also provides energy and carbon for the growth and maintenance of the microbial community. VFA are important by-products of the microbial activity.
Furthermore, in recent years there has been an intense debate about the use of chemicals and antibiotics in feed additives and in many countries a ban on this type of additions to feed additives is being considered. Thus, there is an urgent need for agriculture to develop substances which are in line with reliable and generally accepted practice and not of a medicinal nature.